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: \n, \u{...} - JavaScript | MDN
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  5. : \n, \u{...}
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: \n, \u{...}

Baseline

20157

regex
\f, \n, \r, \t, \v
\cA, \cB, , \cz
\0
\^, \$, \\, \., \*, \+, \?, \(, \), \[, \], {, }, \|, \/

\xHH
\uHHHH
\u{HHH}

: ,

HHH

Unicode 16 xHH 16 2 uHHHH 4 \u{HHH} 16 1 6

\f, \n, \r, \t, \v

\b

\c A Z a z

32 J 74 74 32 10 cJ (\n) 32 \cJ \cj 1 26

\0

U+0000 NUL 8

\^, \$, \\, \. \*, \+, \?, \(, \), \[, \], {, }, \|, \/

\\ \( /

\xHH

Unicode 16 2

\uHHHH

Unicode 16 4 2 Unicode Unicode 2

\u{HHH}

Unicode Unicode 16 1 6

Unicode \a a Unicode

Unicode ]{}

Unicode \cX X _ ASCII \c0 32 \cP \cX X

js
/[\c0]/.test("\x10"); // true
/[\c_]/.test("\x1f"); // true
/[\c*]/.test("\\"); // true
/\c/.test("\\c"); // true
/\c0/.test("\\c0"); // true \c0

js
const pattern = /a\nb/;
const string = `a
b`;
console.log(pattern.test(string)); // true

ECMAScript 2027 LanguageSpecification
# prod-CharacterEscape

MDN

MDN 2025722

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  1. JavaScript
  3. JavaScript
    15. JavaScript
    19. JavaScript
    2. JavaScript
    1. AggregateError
    2. Array
    3. ArrayBuffer
    4. AsyncDisposableStack
    5. AsyncFunction
    6. AsyncGenerator
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    9. Atomics
    10. BigInt
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    14. DataView
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    18. DisposableStack
    19. encodeURI()
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    21. Error
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    23. eval()
    24. EvalError
    25. FinalizationRegistry
    26. Float16Array
    27. Float32Array
    28. Float64Array
    29. Function
    30. Generator
    31. GeneratorFunction
    32. globalThis
    33. Infinity
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    65. Uint8Array
    66. Uint8ClampedArray
    67. Uint16Array
    68. Uint32Array
    69. undefined
    70. unescape()
    71. URIError
    72. WeakMap
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    74. WeakSet
    1. (+)
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    4. async function
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    6. await
    7. (&)
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    9. (~)
    10. (|)
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    14. class
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    17. (--)
    18. delete
    20. (/)
    21. (/=)
    22. (==)
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    25. function
    26. function*
    27. (>)
    28. (>=)
    29. ( )
    30. import.meta
      1. import.meta.resolve()
    31. import()
    32. in
    33. (++)
    34. (!=)
    35. instanceof
    36. (<<)
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    38. (<)
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    40. (&&)
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    42. (!)
    43. (||)
    44. (||=)
    45. (*)
    46. (*=)
    47. new
    48. new.target
    49. null
    50. (??=)
    51. (??)
    54. (?.)
    56. (%)
    57. (%=)
    58. (>>)
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    60. (...)
    61. (===)
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    14. for
    15. for await...of
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    25. switch
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    27. try...catch
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    6. set
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      1. [Symbol.iterator]()
      2. callee
      3. length
    1. constructor
    2. extends
    5. static
    1. : \1, \2
    2. : (...)
    3. : \d, \D, \w, \W, \s, \S
    4. : [...], [^...]
    5. : \n, \u{...}
    6. : |
    7. : ^, $
    8. : a, b
    9. : (?=...), (?!...)
    10. : (?<=...), (?<!...)
    11. : (?ims-ims:...)
    12. : \k<name>
    13. : (?<name>...)
    14. : (?:...)
    15. : *, +, ?, {n}, {n,}, {n,m}
    16. Unicode : \p{...}, \P{...}
    17. : .
    18. : \b, \B
    1. AggregateError: No Promise in Promise.any was resolved
    2. Error: Permission denied to access property "x"
    3. InternalError: too much recursion
    4. RangeError: argument is not a valid code point
    5. RangeError: BigInt division by zero
    6. RangeError: BigInt negative exponent
    7. RangeError: form must be one of 'NFC', 'NFD', 'NFKC', or 'NFKD'
    8. RangeError: invalid array length
    9. RangeError: invalid date
    10. RangeError: precision is out of range
    11. RangeError: radix must be an integer
    12. RangeError: repeat count must be less than infinity
    13. RangeError: repeat count must be non-negative
    14. RangeError: x can't be converted to BigInt because it isn't an integer
    15. ReferenceError: "x" is not defined
    16. ReferenceError: assignment to undeclared variable "x"
    17. ReferenceError: can't access lexical declaration`X' before initialization
    18. ReferenceError: must call super constructor before using 'this' in derived class constructor
    19. ReferenceError: super() called twice in derived class constructor
    20. SyntaxError: 'arguments'/'eval' can't be defined or assigned to in strict mode code
    21. SyntaxError: "0"-prefixed octal literals and octal escape seq. are deprecated
    22. SyntaxError: "use strict" not allowed in function with non-simple parameters
    23. SyntaxError: "x" is a reserved identifier
    24. SyntaxError: \ at end of pattern
    25. SyntaxError: a declaration in the head of a for-of loop can't have an initializer
    26. SyntaxError: applying the 'delete' operator to an unqualified name is deprecated
    27. SyntaxError: arguments is not valid in fields
    28. SyntaxError: await is only valid in async functions, async generators and modules
    29. SyntaxError: await/yield expression can't be used in parameter
    30. SyntaxError: cannot use ?? unparenthesized within || and && expressions
    31. SyntaxError: character class escape cannot be used in class range in regular expression
    32. SyntaxError: continue must be inside loop
    33. SyntaxError: duplicate capture group name in regular expression
    34. SyntaxError: duplicate formal argument x
    35. SyntaxError: for-in loop head declarations may not have initializers
    36. SyntaxError: function statement requires a name
    37. SyntaxError: functions cannot be labelled
    38. SyntaxError: getter and setter for private name #x should either be both static or non-static
    39. SyntaxError: getter functions must have no arguments
    40. SyntaxError: identifier starts immediately after numeric literal
    41. SyntaxError: illegal character
    42. SyntaxError: import declarations may only appear at top level of a module
    43. SyntaxError: incomplete quantifier in regular expression
    44. SyntaxError: invalid assignment left-hand side
    45. SyntaxError: invalid BigInt syntax
    46. SyntaxError: invalid capture group name in regular expression
    47. SyntaxError: invalid character in class in regular expression
    48. SyntaxError: invalid class set operation in regular expression
    49. SyntaxError: invalid decimal escape in regular expression
    50. SyntaxError: invalid identity escape in regular expression
    51. SyntaxError: invalid named capture reference in regular expression
    52. SyntaxError: invalid property name in regular expression
    53. SyntaxError: invalid range in character class
    54. SyntaxError: invalid regexp group
    55. SyntaxError: invalid regular expression flag "x"
    56. SyntaxError: invalid unicode escape in regular expression
    57. SyntaxError: JSON.parse: bad parsing
    58. SyntaxError: label not found
    59. SyntaxError: missing : after property id
    60. SyntaxError: missing ) after argument list
    61. SyntaxError: missing ) after condition
    62. SyntaxError: missing ] after element list
    63. SyntaxError: missing } after function body
    64. SyntaxError: missing } after property list
    65. SyntaxError: missing = in const declaration
    66. SyntaxError: missing formal parameter
    67. SyntaxError: missing name after . operator
    68. SyntaxError: missing variable name
    69. SyntaxError: negated character class with strings in regular expression
    70. SyntaxError: new keyword cannot be used with an optional chain
    71. SyntaxError: nothing to repeat
    72. SyntaxError: numbers out of order in {} quantifier.
    73. SyntaxError: octal escape sequences can't be used in untagged template literals or in strict mode code
    74. SyntaxError: parameter after rest parameter
    75. SyntaxError: private fields can't be deleted
    76. SyntaxError: property name __proto__ appears more than once in object literal
    77. SyntaxError: raw bracket is not allowed in regular expression with unicode flag
    78. SyntaxError: redeclaration of formal parameter "x"
    79. SyntaxError: reference to undeclared private field or method #x
    80. SyntaxError: rest parameter may not have a default
    81. SyntaxError: return not in function
    82. SyntaxError: setter functions must have one argument
    83. SyntaxError: unterminated string literal
    84. SyntaxError: super() is only valid in derived class constructors
    85. SyntaxError: tagged template cannot be used with optional chain
    86. SyntaxError: Unexpected '#' used outside of class body
    87. SyntaxError: Unexpected token
    88. SyntaxError: unlabeled break must be inside loop or switch
    89. SyntaxError: unparenthesized unary expression can't appear on the left-hand side of '**'
    90. SyntaxError: use of super property/member accesses only valid within methods or eval code within methods
    91. SyntaxError: Using //@ to indicate sourceURL pragmas is deprecated. Use //# instead
    92. ReferenceError: deprecated caller or arguments usage
    93. TypeError: 'x' is not iterable
    94. TypeError: "x" is (not) "y"
    95. TypeError: "x" is not a constructor
    96. TypeError: "x" is not a function
    97. TypeError: "x" is not a non-null object
    98. TypeError: "x" is read-only
    99. TypeError: already executing generator
    100. TypeError: BigInt value can't be serialized in JSON
    101. TypeError: calling a builtin X constructor without new is forbidden
    102. TypeError: can't access/set private field or method: object is not the right class
    103. TypeError: can't assign to property "x" on "y": not an object
    104. TypeError: can't convert BigInt to number
    105. TypeError: can't convert x to BigInt
    106. TypeError: can't define property "x": "obj" is not extensible
    107. TypeError: can't delete non-configurable array element
    108. TypeError: can't redefine non-configurable property "x"
    109. TypeError: can't set prototype of this object
    110. TypeError: can't set prototype: it would cause a prototype chain cycle
    111. TypeError: cannot use 'in' operator to search for 'x' in 'y'
    112. TypeError: class constructors must be invoked with 'new'
    113. TypeError: cyclic object value
    114. TypeError: derived class constructor returned invalid value x
    115. TypeError: getting private setter-only property
    116. TypeError: Initializing an object twice is an error with private fields/methods
    117. TypeError: invalid 'instanceof' operand 'x'
    118. TypeError: invalid Array.prototype.sort argument
    119. TypeError: invalid assignment to const "x"
    120. TypeError: Iterator/AsyncIterator constructor can't be used directly
    121. TypeError: matchAll/replaceAll must be called with a global RegExp
    122. TypeError: More arguments needed
    123. TypeError: "x" has no properties
    124. TypeError: property "x" is non-configurable and can't be deleted
    125. TypeError: Reduce of empty array with no initial value
    126. TypeError: setting getter-only property "x"
    127. TypeError: WeakSet key/WeakMap value 'x' must be an object or an unregistered symbol
    128. TypeError: X.prototype.y called on incompatible type
    129. URIError: malformed URI sequence
    130. Warning: -file- is being assigned a //# sourceMappingURL, but already has one
    131. Warning: unreachable code after return statement
    1. JavaScript
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